The aquatic plant Water Canna (Thalia geniculata) is a common ornamental in water gardens. The plant is a favourite with sunbirds that visit for the flower nectar LINK.
An earlier post documented a juvenile Yellow Vented Bulbul (Pycnonotus goiavier) being fed flowers of this plant LINK.
This image by Chia Yeong Kwong shows another adult Yellow-vented Bulbul eating a flower because of the nectar it contains.
Lee Chiu San
To attract birds to a water garden, Thallia dealbata is a better choice than genticulata. This is a slightly larger plant, and its flowers grow on much straighter stalks, not in the obviously zig-zag pattern that you can see in the photo accompanying this article. I have had ponds and water gardens in all my homes, and am also a volunteer who assists in the upkeep of water bodies in a public institution. While Thallia genticulata will attract birds, the attraction rate is far higher when dealbata is planted.
A caution though, is that Thallia plants can be untidy, with many unsightly dead leaves. They should be planted only in areas where they can be easily accessed for pruning.